This invention relates to a system and method of manufacturing a molded article from a settable mixture.
Typically molded articles are fabricated by injecting a settable mixture into a low-pressure mold installed into a molding machine. Bathtubs, and shower combinations and other large items are formed using this type of molding operation. Typically, the settable mixture includes a three-part mixture composed of a catalyst, a matrix polymer and a foaming agent.
In some manufacturing operations a preformed laminate is inserted into the mold and the settable mixture is injected into the mold and bonds to the preformed laminate to obtain the surface finish of the molded article. Another method of obtaining the desired surface finish of the molded article is to spray a surface coating onto the mold immediately before the molding operation. This method requires the application of the surface coating at a location substantially close to the molding operation such that within a limited time the mold is injected with the settable mixture. Emissions from the application of the surface coating are subject to government regulation and typically required to be separated from the molding operation such as in a spray booth having air scrubbers and other air treatment devices.
For these reasons it is desirable to develop a system and method of manufacturing a molded article where the surface coating may be applied to the mold sufficiently close to the mold while preventing emissions from the application process from interfering with the molding operation.
The invention is a system and method of producing a molded article from a settable mixture in a low pressure molding process including a mold having a fixed part disposed at a molding station and a movable part shuttled between the mold station and a spray station separated from the mold station by a retractable enclosure such that emissions from the spray station are separate from the molding process.
The system and method includes the application of a surface coating to a movable part of a mold at a spray station. During application of the surface coating at the spray station an enclosure around the spray station contains emissions from the spraying process. Once the surface coating is applied to the movable part of the mold the enclosure is retracted and the movable part of the mold shuttles to the mold station and is secured to the fixed part of the mold. The settable mixture is injected into the mold to form the molded article and bond with the surface coating. The mold is rotated during injection of the settable mixture to encourage the evacuation of air from the mold as the settable mixture fills the mold cavity. This feature is best described in co-pending patent application Ser. No. 10/134,231 entitled xe2x80x9cVariable Feedback Molding Systemxe2x80x9d. Upon completion of the molding operation the movable part of the mold shuttles away from the mold station and the molded article is removed from the mold. A track system enables movement of the mold parts between the stations. In alternate embodiments of the manufacturing system the track interconnects multiple mold stations to a single common spray station such that emissions from the application of the surface coating are confined to one location and multiple mold stations provide increased manufacturing efficiencies.
The system and method of the subject invention provides for the manufacturing of a molded article having a surface coating applied sufficiently close to the mold station while preventing emissions from interfering with the molding operation and increasing manufacturing efficiency.